This invention relates generally to the field of electronic devices and systems, and more specifically to optical switching technology.
A relay or switch may be used to change an optical signal from a first state to a second state. In general there may be more than two states. In applications that require a small switch geometry or a large number of switches within a small region, microfabrication techniques may be used to create switches with a small footprint. A microfabricated switch may be used in a variety of applications, such as industrial equipment, telecommunications equipment and control of electromechanical devices such as ink jet printers.
In switching applications, the use of piezoelectric technology may be used to actuate a switch. Piezoelectric materials have several unique characteristics. A piezoelectric material can be made to expand or contract in response to an applied voltage. This is known as the indirect piezoelectric effect. The amount of expansion or contraction, the force generated by the expansion or contraction, and the amount of time between successive contractions are important material properties that influence the application of a piezoelectric material in a particular application. Piezoelectric material also exhibits a direct piezoelectric effect, in which an electric field is generated in response to an applied force. This electric field may be converted to a voltage if contacts are properly coupled to the piezoelectric material. The indirect piezoelectric effect is useful in making or breaking a contact within a switching element, while the direct piezoelectric effect is useful in generating a switching signal in response to an applied force.
A method and structure for an optical switch is disclosed. According to a structure of the present invention, a chamber is housed within a solid material. A plurality of wetting pads within the chamber are coupled to the solid material, while a plurality of piezoelectric elements within the chamber are also coupled to the solid material. A slug within the chamber is coupled to one or more of the plurality of wetting pads and may be further coupled to one or more of the plurality of piezoelectric elements. The slug moves within the chamber and makes or breaks surface tension connections with one or more of the plurality of wetting pads. A liquid metal within the gas-filled chamber is coupled to the slug, and coupled to the plurality of wetting pads. The liquid metal, such as mercury or a Gallium alloy, acts as a friction-reducing lubricant, and also is operable to provide a surface tension that maintains a connection between the slug and a contact of the plurality of wetting pads.
According to a method of the present invention, one or more of the plurality of piezoelectric elements are actuated, with the actuation of the one or more piezoelectric elements causing the one or more piezoelectric elements to contact the slug and move the slug from a first number of wetting pads to a second number of wetting pads. The first number of wetting pads and the second number of wetting pads are wetted by the liquid metal. The movement of the slug from the first number of wetting pads to the second number of wetting pads breaks a liquid metal surface tension between the slug and the first number of wetting pads and establishes a coupling between the slug and the second number of wetting pads. The position of the slug and the wetting of the slug by the liquid metal enables a reflective surface to be created by the liquid metal. The reflective surface is created at an angle that allows signals to be coupled between the first set of optical waveguides and the second set of optical waveguides. The surface tension of the liquid metal between the slug and the second number of wetting pads is then operable to maintain a coupling between the second number of wetting pads and the slug which also maintains the reflective surface.